Persistent expression of BMP-4 in embryonic chick adrenal cortical cells and its role in chromaffin cell development.
BACKGROUND
Adrenal chromaffin cells and sympathetic neurons both originate from the neural crest, yet signals that trigger chromaffin development remain elusive. Bone morphogenetic proteins (BMPs) emanating from the dorsal aorta are important signals for the induction of a sympathoadrenal catecholaminergic cell fate.


RESULTS
We report here that BMP-4 is also expressed by adrenal cortical cells throughout chick embryonic development, suggesting a putative role in chromaffin cell development. Moreover, bone morphogenetic protein receptor IA is expressed by both cortical and chromaffin cells. Inhibiting BMP-4 with noggin prevents the increase in the number of tyrosine hydroxylase positive cells in adrenal explants without affecting cell proliferation. Hence, adrenal BMP-4 is likely to induce tyrosine hydroxylase in sympathoadrenal progenitors. To investigate whether persistent BMP-4 exposure is able to induce chromaffin traits in sympathetic ganglia, we locally grafted BMP-4 overexpressing cells next to sympathetic ganglia. Embryonic day 8 chick sympathetic ganglia, in addition to principal neurons, contain about 25% chromaffin-like cells. Ectopic BMP-4 did not increase this proportion, yet numbers and sizes of 'chromaffin' granules were significantly increased.


CONCLUSIONS
BMP-4 may serve to promote specific chromaffin traits, but is not sufficient to convert sympathetic neurons into a chromaffin phenotype.
Huber
Katrin
K
Neuroanatomy, Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany. huber@ana.uni-heidelberg.de
Franke
Aylin
A
Brühl
Barbara
B
Krispin
Shlomi
S
Ernsberger
Uwe
U
Schober
Andreas
A
von Bohlen und Halbach
Oliver
O
Rohrer
Hermann
H
Kalcheim
Chaya
C
Unsicker
Klaus
K
D000311:Adrenal Glands / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics*; D052005:Bone Morphogenetic Protein Receptors, Type I / Q000378:metabolism; D016466:CHO Cells; D049109:Cell Proliferation; D002642:Chick Embryo; D019439:Chromaffin Cells / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D005455:Fluorescent Antibody Technique; D005728:Ganglia, Sympathetic / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008854:Microscopy, Electron; D009474:Neurons / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D011247:Pregnancy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054339:Steroidogenic Factor 1 / Q000235:genetics; D046509:Tissue Culture Techniques; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism
D055415:Bone Morphogenetic Protein 4; D054339:Steroidogenic Factor 1; D014446:Tyrosine 3-Monooxygenase; D052005:Bone Morphogenetic Protein Receptors, Type I